In the scorching drama Rampart, Woody Harrelson takes to his role as Dave Brown, dirty LAPD cop, like a starving man to a groaning banquet table. Co-written by director Oren Moverman and James Ellroy, Rampart, named after the infamous division that imploded under allegations of massive corruption, is set in 1999, the year that scandal unfolded. Brown is more "bent for the job" than "bent for himself", but his excesses make front-page news after he's filmed brutally beating a suspect, Rodney King-style.

The movie chronicles the personal apocalypse of a man whose lucky streak is running out, who chugs scotch in his squad car; maintains dual households with two ex-wives (Cynthia Nixon and Anne Heche), sisters by whom he has a kid apiece; and routinely short-cuts his way to convictions or frame-ups. But now Internal Affairs are on his back, and Brown's hitherto charmed life is starting to unravel at breakneck pace.

Fine as the film is, it reminds me how lucky the movie business is to be situated in the same town as a police department consistently deemed – until recently – among the most corrupt and racist in the nation. Because of that simple accident of geography, Hollywood has had a ringside seat to the nightmarish ongoing cop show that has given us the 1965 and 1992 anti-police uprisings (each the most violent in the nation's history when they unfolded), the horrors of Rampart Division and the stubborn recalcitrance of the force when confronted with reforming chiefs.

Thus, on screens large and small, the LAPD is now a genre unto itself, and the wider cop genre is routinely reinvigorated by LAPD movies and TV shows. The template was Dragnet, the department-backed TV whitewash that never touched on reforming chief William Parker's firm belief in the racial inferiority of the city's non-white citizens, and Adam-12, set in a fictionalised Rampart Division. Serving officer Joseph Wambaugh humanised the cop life in the 70s with his novels The Blue Knight and The New Centurions and their movie adaptations, while Ellroy – an LAPD fan, incredibly – has blackened the force's name in novel after novel (reminding us, inter alia, that in the 1940s police nightsticks were routinely referred to as "nigger-knockers"). Hill Street Blues revolutionised cop TV in ways that are still felt 30 years later – particularly in the superb Southland. LA Confidential, based on an Ellroy novel, had a similar, albeit retrospective effect on perceptions.

Rampart itself juiced the genre up no end, giving us Training Day and The Shield, in which the Rampart Division (renamed at the LAPD's request) is simply the baddest gang in town. Rampart the movie joins this same lineage.

It's the wild west out here: as Nick Nolte's crooked cop says in Mulholland Falls before tossing a mobster off a cliff, "This isn't America, pal. This is LA!"